Changes in intracellular Na+ concentration evoked by nicotinic receptor activation in the guinea-pig adrenal chromaffin cells.
Using the whole-cell voltage clamp technique and microfluorometry with sodium-binding benzofuran isophthalate (SBFI), a nicotine-induced inward current and increase in the intracellular Na+ concentration ([Na+]in) were examined simultaneously in guinea-pig adrenal chromaffin cells. The increase in [Na+]in expected from the time-integrated inward current was well correlated with that of [Na+]in measured with SBFI. The ratio of the expected [Na+]in to the measured [Na+]in was 0.64 at -85mV and decreased with increasing holding potentials. The decay time constant of the increased [Na+]in was not affected by ouabain. It is concluded that the Na+ entering the cell is diffusable in about 60% cell volume without fast buffering mechanisms and is eliminated by the exchange of Na+ between the pipette solution and cell interior under the patch clamp condition.
Ito
S
S
Laboratory of Pharmacology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan. sito@vetmed.hokudai.ac.jp
Ohta
T
T
Nakazato
Y
Y
D000818:Animals; D019439:Chromaffin Cells / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009538:Nicotine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000502:physiology
D011978:Receptors, Nicotinic; D010042:Ouabain; D009538:Nicotine; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase